Islamic State’s affiliate in Libya has capitalized on the battlefield failures and disillusionment among better-established, more moderate Islamist groups in the country, following the same formula that brought the radical movement success in Syria and Iraq, Western counterterrorism officials said. A group calling itself Islamic State’s Tripoli Province claimed responsibility for an attack on Tuesday on a hotel that killed nine people, including an American. It was the first time the group came to prominence in Libya, raising concerns that the reach of the extremists is spreading beyond Syria and Iraq. But the attacks also underlined the threat Islamic State poses to more entrenched Islamist groups such as Libya Dawn, a more moderate Islamist militia that is ideologically close to Egypt’s Muslim Brotherhood and now fights […]